The invention fits within the Technology field, comprised of devices and/or systems used to dewater boreholes drilled for bench-blasting in quarries and mines.
Water, coming from rain and ground filtration, accumulates very frequently inside boreholes. The presence of water inside a borehole is a serious problem that causes difficulty in loading explosives, reduces their performance and substantially increases the cost of blasting, since the use of more expensive water-resistant explosives is needed.
This invention intends to provide the user of explosives for bench-blasting (in quarries, mines, public works, etc.) with a useful and easy-to-use technical solution that also reduces the possibility of the water extraction system getting stuck, or lost inside the borehole.
All the inventions included in this field of technology can be classified into two main groups:                1. Continuous Systems, such as submersible pumps, and those systems making use of the Venturi Effect.        2. Discontinuous Systems, by which borehole water extraction is carried out in several repetitive cycles.        
As a result of the Report of the State of the Art and Previous Examination elaborated by the OEPM, Inventions U.S. Pat. No. 3,647,319 (in forward D1) and U.S. Pat. No. 3,971,437 (in forward D2) are mentioned as the two closest ones to the Invention proposed in this document. Other inventions mentioned by the OEPM were DE 4005574 A1 and U.S. Pat. No. 6,672,392B2.
Pursuant to the previous classification, D2 would be a Continuous System.
Inventions Ref: 397942, D1, ES 2253970, and the present invention P200600704, would be classified as Discontinuous Systems. Within this group, there is a special mention for the sub-group made up of those systems using the physical principle of Pneumatic Displacement as the means to displace water from the borehole. Inventions Ref. 397942, D1, and P200600704 are included in this sub-group. Attention is also drawn to the existence of another sub-division within this Group, made up of those inventions using a vacuum circuit alternately with a compressed-air circuit. This specific design incorporates important operative improvements, despite the resultant major complication in the final design of the invention. Another differentiating feature is that only the Invention P200600704 described in this document can be included in this sub-division. Inventions DE 4005574A1 and U.S. Pat. No. 6,672,392B2 are not related to this specific Technology field (boreholes dewatering) and, therefore, cannot be included in the classification above.
Differences Between P200600704 and D1.
According to what is stated in the original description document of D1, there are substantial differences between the above-mentioned invention (D1) and P200600704, that give this invention substantial operative advantages:
1. A constant clearance is left between the dewatering system and the borehole along its whole length, reducing the risk of the extraction system becoming stuck or lost inside the borehole.
In P200600704, the body of the pump consists of a double hose (1)+(15) with a constant external section. This double hose is inserted into the borehole from a hose reel placed in proximity to the borehole, and it covers its entire length. Thus, a sufficient clearance is left between the internal walls of the borehole and the external face of the hose.
This clearance is kept constant, without any bulges, throughout the length of the borehole.
In contrast, D1 is described as a tubular body (tube) closed at its top end, and inserted into the borehole. It remains connected to the outside by means of two pneumatic hoses with a smaller diameter than that of the tubular body. Therefore, this design, does not maintain a constant clearance between the dewatering system and the borehole along its full length, having a critical point located in the aperture created by the intersection between the tubular body and the two hoses that hold it from the outside. Experience and practice show that those systems that cannot leave a constant clearance between the device and the inner walls of the borehole are very prone to becoming stuck in its interior, resulting in the loss of the device as it cannot then be retrieved.
2. Invention P200600704 uses a flexible hose to confine the volume to be pressurized through the use of a hermetically sealed cap that is placed on the outside of the borehole and any vertical protrusion from the borehole. There is a clear benefit in using a flexible hose because it is easier to extract the hose despite encounters with any obstacles on its way to the surface.
By contrast, D1 uses a rigid tube that, due to the normal conditions of drilling, can never have a length exceeding two or two and a half meters. Since a borehole is never completely straight, it is very difficult to repeat the action of insertion and extraction of the tube. This forces Invention D1, to keep its closing cap located inside the borehole.
3. Vacuum Phase in Invention P200600704: Substantial Improvement in the Performance of Water Extraction Cycles.
The introduction of a Vacuum phase as a part of the dewatering cycles is a fundamental innovation that has not been considered in any previous invention in this field of Technology. This Vacuum phase brings a substantial improvement in the performance of dewatering cycles. This improvement becomes significant in the final cycles, when a smaller volume of water remains in the interior of the borehole, and would normally be very difficult to extract.
Differences Between P200600704 and Other Inventions Mentioned by the OEPM
Invention D2, mentioned in the Report of the Preliminary Study (OEPM), patent (U.S. Pat. No. 3,971,437) in 1976, describes a system similar to the Invention Ref 397942, as it also produces an effect of hermetic sealing against the walls of the borehole. This is done by means of a bladder that is filled with compressed air. Therefore, this cannot be considered to represent any system equivalent to P200600704 (thus excluding its inventive applicability).
In summary, Inventions DE 4005574 A1 and U.S. Pat. No. 6,672,392 B2 cannot be included within this Technology field as they can never be used to dewater boreholes for bench-blasting:
                Both inventions are permanently fixed to the ground by means of a casing (DE 4005574 A1) or by means of a set of metallic pipes (U.S. Pat. No. 6,672,392 B2). By contrast, P200600704 is never fixed to the ground, keeping a clearance between the hose and the inner walls of the borehole along its whole length.        Both inventions make use of rigid tubes to extract water. By contrast, P200600704 uses a flexible hose to dewater the boreholes.        The objects of these inventions are not related at all to borehole dewatering for bench-blasting:                    Extracting water from a large diameter well-hole, in the case of invention DE 4005574 A1            Extracting water and gas from a large diameter well-hole in a gas field, in the case of invention U.S. Pat. No. 6,672,392 B2.                        